1. Field of the Invention
The present invention relates to rail segments and a method for wiring feeder cables onto elevated rails such as monorails, which transfer conveyor carriages.
2. Description of the Related Art
There are monorail type carriages, which move along elevated rails suspended from the ceiling of a factory or a warehouse to transport articles between stations. There is a system for feeding electric power to such carriages, which has a feeder cable extending along a rail and a secondary coil opposed to the feeder cable in a non-contacting manner. Alternating current flowing through the feeder cable generates electromagnetic induction in the secondary coil, which is used to drive the carriages (Japanese Unexamined Patent Publication No. 6-153305).
FIG. 13 shows a carriage 1 that employs the above power feeding system. The carriage 1 is suspended from a rail R by a plurality of rollers 2, 3. A feeder cable 4 looped into two portions extends beside the rail R. The carriage device 1 moves with its receiving core 5 opposed to the feeder cable 4. The high frequency current flowing through the feeder cable 4 induces electromotive force in a secondary coil 6, which is wound around the receiving core 5. The electromotive force applies drive force to a motor 7, which drives the carriage 1.
To suspend the rail R, as shown in FIG. 14, rail members 51, which have a length of several meters, are connected to one another along the route of the carriage 1 before suspension. A high lift work vehicle is used to install the rail R. The rail members 51 are supported by support members that are attached to the ceiling or support posts that are erected on the ground. The feeder cable 4 is wired to the rail R after installation.
When wiring the rail R, a wound electric cable 52 is straightened on the ground in correspondence with the rail. An end of the electric cable 52 is then lifted to wire the rail R from its end. The electric cable 52 is fitted to support members 53 that are attached beside the rail members 51 with a predetermined interval between one another.
However, the electric cable 52, which feeds electric power to the carriage 1, is of a standard for high frequency current and has a relatively large diameter (for example, a diameter ranging from 2 to 3 cm). Thus, the electric cable 52 weighs as much as 1 kg or more per meter. Furthermore, the rail R is normally suspended at a position that is three to four meters or more above ground. It is thus necessary to lift the electric cable 52 having a length of several tens of meters, three to four meters or more high continuously from the end of the electric cable 52. The heavy electric cable 52 cannot be lifted and wired using only manual labor in the same manner as normal wiring. Therefore, it is necessary to use large scale equipment (a high lift work vehicle used at electric construction sites) in such constructions. This requires enormous work and a great deal of time.